Air filter element and method of producing the same

ABSTRACT

There is provided an air filter element which is used by fitting a central opening in its end plate on a cylindrical portion projecting into a casing, wherein the air filter element has a novel seal construction (end plate). An end plate ( 10 ) closing the end surface of a hollow cylindrical filter portion ( 2 ) includes a soft inner peripheral seal portion ( 11 ) capable of sticking to the outer surface of a cylindrical member ( 33 ) and a rigid closure portion ( 13 ) which is disposed on the outer periphery side of the inner peripheral seal portion and in which the end surface of the filter portion is embedded, the end plate being of composite construction in which the inner peripheral seal portion ( 11 ) and the closure portion ( 13 ) are integrally molded. On the outer periphery side of the inner peripheral seal portion ( 11 ), a groove ( 12 ) axially extending from an end surface ( 10   a ) of the end plate is formed along the opening. The inner peripheral seal portion ( 11 ) effects reliable center seal with respect to the cylindrical member ( 33 ), while the closure portion ( 13 ) on the outside thereof improves the rigidity of the air filter element.

TECHNICAL FIELD

The present invention relates to an air filter element which is used byfitting a central opening in an end plate thereof on a cylindricalmember projecting into a casing of an air cleaner or air filter and,more particularly, to an air filter element suitable for an internalcombustion engine, and a method of producing the same.

BACKGROUND ART

As an air cleaner used for an internal combustion engine or the like, anair cleaner in which an air filter element having a cylindrical filterportion is installed to an air outlet (cylindrical member) projectinglyformed in a casing to be contained in the casing is known. In this airfilter element, both end surfaces of the hollow cylindrical filterportion are closed by end plates, and an opening for causing a fluid topass through is formed in the center of at least one end plate, by whichthe air filter element is used by fitting the opening on the air outlet.Air is introduced from the outside of the casing into a space formed onthe outside of the air filter element in the casing, caused to passthrough from the outside to the inside in the cylindrical filterportion, and purified air is discharged from an inside space (filterchamber) of the air filter element to the outside of the casing throughthe air outlet.

Seal between the air filter element and the casing, which is necessaryto prevent contaminated air from flowing into the filter chamber, isprovided by the end surface of the end plate which is installed to theair outlet (end surface side of filter portion) and the inner surface ofthe casing opposed to the end plate (axial seal), by the opening of theend plate (inner periphery side of filter portion) and the outer surfaceof the air outlet (center seal (O-ring etc.)), or by both of them. U.S.Pat. No. 4,720,292 has disclosed an air filter using center seal.

An object of the present invention is to provide an air filter elementhaving a novel seal construction (end plate construction) in which sealbetween an air filter element and a casing is provided between anopening of an end plate and the outer surface of an air outlet(cylindrical member), and a method of producing the air filter element.

DISCLOSURE OF THE INVENTION

In an air filter element in accordance with the present invention, anend plate, which closes the end surface of a hollow cylindrical filterportion and is formed, in the center thereof, with an opening that isfitted on a cylindrical member, includes a soft inner peripheral sealportion capable of sticking to the outer surface of the cylindricalmember and a rigid closure portion which is disposed on the outerperiphery side of the inner peripheral seal portion and in which the endsurface of the filter portion is embedded, the end plate being ofcomposite construction in which the inner peripheral seal portion andthe closure portion are integrally molded.

The phrase “integrally molded” means that the inner peripheral sealportion and/or the closure portion are fixed to and integrated with eachother by molding using a synthetic resin without the use of an adhesive.

The end plate is made up of the soft inner peripheral seal portion andthe rigid closure portion in which the end surface of filter portion isembedded, the end plate being of composite construction in which theinner peripheral seal portion and the closure portion are integrallymolded. Therefore, center seal (radial seal in the center of the filterelement) is provided reliably with compression of the inner peripheralseal portion. Also, since the filter portion is firmly fixed by therigid closure portion, the rigidity of air filter element is enhanced.Since the end plate consists of composite construction in which the softinner peripheral seal portion and the rigid closure portion areintegrally molded without the use of an adhesive, the bonding of theseportions is strong, and hence the seal portion is not separated.

Comparing with the case where the whole of the end plate is molded usinga soft material such as elastomer, a sufficient strength can beobtained, and the strength is improved. Therefore, the thickness of theend plate can be decreased, which leads to an increase in filter area.Also, if the whole of the end plate is molded using a soft expandedmaterial, poor molding such as a void (cavity or dent in outer surface)occurs easily. The method in accordance with the present invention cansolve this problem.

Also, in a preferred mode, on the outer periphery side of the innerperipheral seal portion (11), a groove (12) axially extending from theend surface of the end plate (10) is formed along the opening (18), andon the outer periphery side of the groove, the closure portion (13) isformed. By this configuration, reliable center seal is provided by thecompression and deflection of the inner peripheral seal portion causedby the cylindrical member. By adjusting the dimension of groove, thedegree of deflection of the inner peripheral seal portion can beadjusted. When the air filter element is pulled out at the time ofreplacement after use, it can be pulled out easily owing to thedeflection of the inner peripheral seal portion.

By providing a plurality of ribs, which connect the inner peripheralseal portion and the closure portion to each other, in the groove, theshape of the inner peripheral seal portion can be held by the ribs, andalso the degree of deflection of the inner peripheral seal portion canbe adjusted.

The air filter element in accordance with the present invention can beproduced easily and reliably by pouring a synthetic resin material,which is soft after curing, to the inner periphery side of a ring-shapedconcave portion in a mold formed with the ring-shaped concave portionfor molding the end plate, by pouring a synthetic resin material, whichis rigid after curing, to the outer periphery side of the ring-shapedconcave portion, and by inserting the end surface of the filter portionis inserted into the ring-shaped concave portion to integrally cure bothof the synthetic resin materials. Also, the air filter element inaccordance with the present invention can be produced by disposing asoft seal member having been molded in advance on the inner peripheryside of the ring-shaped concave portion in the mold, by pouring asynthetic resin material, which is rigid after curing, to the outerperiphery side of the ring-shaped concave portion, and by inserting theend surface of the filter portion into the ring-shaped concave portionto cure the synthetic resin material integrally with the seal member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of an air filter element 1 inaccordance with Example 1;

FIG. 2 is an enlarged sectional view of a part of an end plate 10 inaccordance with Example 1;

FIG. 3 is a bottom view of an air filter element 1 in accordance withExample 1;

FIG. 4 is a sectional view showing a state in which an air filterelement 1 in accordance with Example 1 is contained in a casing 30;

FIG. 5 is an explanatory view illustrating a method of producing an airfilter element 1 in accordance with Example 1; and

FIG. 6 is an explanatory view illustrating a method of producing an airfilter element 1 in accordance with Example 1.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will now be described in detailwith reference to the accompanying drawings. The same reference numeralsare applied to the same elements, and duplicated explanation is omittedappropriately.

Example 1

FIG. 1 is a longitudinal sectional view of an air filter element 1 inaccordance with Example 1, and FIG. 2 is an enlarged sectional view of apart of an end plate 10. The air filter element 1 has a hollowcylindrical filter portion 2 and the end plates 10 and 20 for closingboth end surfaces of the filter portion 2. In the center of one endplate 10, an opening 18 is formed to discharge a fluid that has passedthrough the filter portion 2 and has been filtered. The air filterelement 1 is used by fitting the opening 18 on a cylindrical member (airoutlet) 33, described later. The construction of the other end plate 20is not subject to any special restriction. In this example, the endplate 20 is formed by one plate-shaped member having a closing portion20 a for separating a filter chamber (inside space of the filter portion2) 3 from an outside space, which closes the whole of one end surface ofthe air filter element 1 as a whole. In the filter portion 2, asheet-shaped filter material such as filter paper or nonwoven fabricappropriately folded into a chrysanthemum shape in cross section ispreferably used. A wound sheet-shaped filter material or other typesthereof can be used, and the type of the filter material is not subjectto any special restriction. Also, in the example shown in Figure, aporous tube 5 is disposed on the outer peripheral surface of the filterportion 2 so as to be embedded in the closure portion 13. However, asupport member such as the porous tube 5 may be disposed in an arbitraryposition, and may be disposed on the outer peripheral surface and/or theinner peripheral surface of the filter portion 2.

The end plate 10 is made up of a soft inner peripheral seal portion 11and a rigid closure portion 13 for closing an end surface 2 b of thefilter portion 2, the end plate being of composite construction in whichthe inner peripheral seal portion 11 and the closure portion 13 areintegrally molded. The opening 18 in the end plate 10 is formed by thesoft inner peripheral seal portion 11 capable of sticking to the outersurface of the cylindrical member 33. In the rigid closure portion 13,the end surface 2 b of the filter portion 2 is embedded and fixed toclose the end surface 2 b of the filter portion 2.

On the outer periphery side of the inner peripheral seal portion 11 (onthe outside in the radial direction of filter element), a groove 12axially (in the height direction) extending from an end surface 10 a ofthe end plate 10 is formed along the opening 18.

As shown in FIG. 2, the groove 12 is located on the inside in the radialdirection of an inner peripheral surface 2 a of the filter portion 2,and the deepest portion (bottom portion 12 a) of the groove is locatedon the inside in the axial direction of the end surface 2 b of thefilter portion 2. The groove 12 is formed into a ring shape along theopening 18. The groove 12 is formed so that the groove width decreasestoward the bottom portion 12 a. The inside wall of the groove 12 isformed by the inner peripheral seal portion 11, and the outside wall ofthe groove 12 is formed by the rigid closure portion 13. On the outsidein the radial direction of the groove 12, the closure portion 13 isformed to close the end surface 2 b of the filter portion 2.

By forming the groove 12, the inner peripheral seal portion 11 candeflect. An outer wall 11 a of the inner peripheral seal portion 11forms the inside wall of the groove 12, and has a height correspondingto the depth of the groove 12. An inner wall 11 b of the innerperipheral seal portion 11 forms the opening 18, and is formed so as tobe higher than the depth of the groove 12. Also, the inner wall 11 b ofthe inner peripheral seal portion 11 is formed into a tapered shape sothat the opening diameter decreases toward the inside in the axialdirection. The shape of the inner wall 11 b (inner peripheral surfaceshape) is not subject to any special restriction if it sticks to theouter surface of the cylindrical member to fulfil sealing function. Theinner wall 11 b may be formed appropriately so as to have a convexportion or a concave portion (step portion).

A top surface 11 c of the inner peripheral seal portion 11 extends tothe outside in the radial direction so as to cover the bottom portion 12a of the groove 12, and is connected to the rigid closure portion 13.The inner peripheral seal portion 11 extends to the inner periphery sidefrom a position above the bottom portion 12 a of the groove 12, andthereafter extends to the outside in the axial direction by being bentinto a hook shape. The inner peripheral seal portion 11 substantiallyhas an L shape in cross section as a whole. On the inside of the groove12, the cross section of the inner peripheral seal portion 11 is formedinto a trapezoidal shape which is long in the axial direction.

The inner peripheral seal portion 11 is formed of an elastic materialsuitable for fulfilling the sealing function, for example, a softexpanded synthetic resin, preferably expanded urethane resin etc. Therigid closure portion 13 is formed of a synthetic resin more rigid thanthe inner peripheral seal portion 11, for example, rigid (not elastic)urethane resin, etc. The closure portion 13, which is a rigid syntheticresin portion, does not take part in sealing between the air filterelement and the casing, so that it is formed of a material that is morerigid than the inner peripheral seal portion 11, hardly havingelasticity, and is unsuitable for fulfilling the sealing function. Ifthe soft inner peripheral seal portion and the rigid closure portion areformed of the same kind of material, for example, if the soft innerperipheral seal portion is formed of soft expanded urethane resin andthe rigid closure portion is formed of rigid urethane resin, thecombination of these materials enables more strongly integral molding.The soft expanded synthetic resin consisting of expanded urethane resinetc. which has a surface hardness of about 30 to 50 (ASKER C) and therigid synthetic resin consisting of rigid expanded urethane resin etc.which has a surface hardness of about 35 to 55 (SHORE D) (for example,measured in accordance with JIS K-6301) are preferably used.

The boundary between the soft inner peripheral seal portion 11 and therigid closure portion 13 need not necessarily be formed definitely asshown in Figure, and the boundary position can be changed appropriately.As will be described later, a concave portion 15 formed in the centralportion in the radial direction of the end surface of the rigid closureportion 13 is formed to determine the position of the end surface 2 b ofthe filter portion 2, and is formed continuously in an annular shape orpartially.

As shown in FIG. 3, a plurality of ribs 16 may be formed in the groove12 to connect the inner peripheral seal portion 11 and the closureportion 13 to each other. The ribs 16 can hold the shape of the innerperipheral seal portion 11, and can adjust the degree of deflection ofthe inner peripheral seal portion 11. The ribs 16 are molded integrallywith the inner peripheral seal portion 11 and the closure portion 13 byusing a synthetic resin material.

FIG. 4 shows a state in which the above-described air filter element 1is contained in a cylindrical casing 30. On the outer periphery side ofthe air filter element 1 in the casing 30 is formed a non-purified airchamber 31, and on the inner periphery side of the filter portion 2 isformed a filter chamber 3. At the side wall of the casing 30, an inlet32 communicating with the non-purified air chamber 31 is formed. In thecenter of one end portion of the casing 30, the cylindrical member (airoutlet) 33 communicating with the filter chamber 3 is formedprojectingly in the casing. On the outside in the radial direction ofthe cylindrical member 33, a casing bottom surface 34 is formed.

The opening 18 formed by the inner peripheral seal portion 11 is fittedon the cylindrical member 33 to contain the air filter element 1 in thecasing 30. Since the inner wall 11 b of the inner peripheral sealportion 11 is formed into a tapered shape so that the opening diameterdecreases toward the inside in the axial direction of the air filterelement, the air filter element can be fitted easily on the cylindricalmember 33.

Since the opening 18 is formed by the soft inner peripheral seal portion11 capable of sticking to the outer surface of the cylindrical member33, reliable center seal is provided by the compression and deflectionof the inner peripheral seal portion 11 caused by the cylindrical member33. Also, since the filter portion 2 is firmly fixed by the rigidclosure portion 13, the rigidity of the air filter element 1 isenhanced.

The outside air is introduced into the non-purified air chamber 31 inthe casing 30 through the inlet 32, and is caused to pass through thefilter portion 2 of the air filter element 1, by which dust in the airis arrested. The purified air passes through the filter chamber 3 and isdischarged to the outside of the casing 30 through the air outlet 33,being introduced to an internal combustion engine or the like, notshown.

Although a case where a fluid is filtered from the outside to the insidein the radial direction of the filter portion 2 has been explained inthe above description, the present invention can be applied to a casewhere a fluid is filtered from the inside to the outside in the radialdirection of the filter portion 2 (a case where the cylindrical member33 serves as an air inlet).

Next, a preferred method of producing the above-described air filterelement 1 will be described. FIG. 5 is an explanatory view illustratinga method of producing the air filter element 1, in which referencenumeral 40 denotes a top face open type mold for molding.

The mold 40 is provided with a ring-shaped inner peripheral concaveportion 41 for molding the soft inner peripheral seal portion 11, aring-shaped convex portion 42 for molding the groove 12, and aring-shaped outer peripheral concave portion 43 for molding the rigidclosure portion 13 successively from the inside in the radial direction.A convex portion 45 provided at the bottom of the ring-shaped outerperipheral concave portion 43, which is used to mold the concave portion15 of the end plate 10, is formed to determine the position of the endsurface 2 b of the filter portion 2. The convex portion 45 is formedcontinuously in an annular shape or partially. The ring-shaped convexportion 42 is formed so as to be higher than the convex portion 45. Inorder to form the above-described ribs 16, the ring-shaped convexportion 42 has only to be eliminated partially.

As shown in FIG. 5, a predetermined amount of a synthetic resin material50, which is soft after curing, is poured into the ring-shaped innerperipheral concave portion 41 through an injection nozzle 60, and apredetermined amount of a synthetic resin material 51, which is rigidafter curing, is poured into the ring-shaped outer peripheral concaveportion 43 through an injection nozzle 61. The sequence of pouringoperations is not subject to any special restriction. Both pouringoperations may be performed at the same time. The ring-shaped convexportion 42 prevents the synthetic resin material 50, which is soft aftercuring, and the synthetic resin material 51, which is rigid aftercuring, from being mixed inadvertently with each other.

After both of the synthetic resin materials 50 and 51 are poured andbefore they are cured, the end surface of the cylindrical filter portion2, which is in a semifinished state, is inserted into the syntheticresin material 51 which has been poured into the ring-shaped outerperipheral concave portion 43 so as to dip into the synthetic resinmaterial 51 as shown in FIG. 6, by which both of the synthetic resinmaterials 50 and 51 are integrally cured. It is preferable that the softsynthetic resin material 50 in the ring-shaped inner peripheral concaveportion 41 be caused to overflow to the rigid synthetic resin material51 side to be cured integrally with the synthetic resin material 51. Atthe time of curing, the synthetic resin materials are usually heated.After curing, the filter portion 2 is taken out of the mold 40. Thereby,the end plate 10 of composite construction in which the soft innerperipheral seal portion 11 and the rigid closure portion 13 in which theend surface of the filter portion 2 is embedded are integrally moldedcan be obtained. After or before that, the opposite end surface of thefilter portion 2 is closed.

The position of boundary between the soft inner peripheral seal portion11 and the rigid closure portion 13 can be changed by controlling theviscosity, pouring speed, pouring amount, pouring position, etc. of eachsynthetic resin material 50, 51. Pouring operation of both of thesynthetic resin materials 50 and 51 is usually performed while the mold40 is rotated around the center of the mold. The synthetic resinmaterials 50 and 51 can be poured simultaneously or successively.Simultaneous pouring operation simplifies the process and shortens theoperation time.

The embodiment of the present invention has been described by takingexamples. The present invention is not limited to the above-describedembodiment, and various additions and modifications can be made withoutdeparting from the spirit and scope of the present invention.

INDUSTRIAL APPLICABILITY

As described above, the air filter element in accordance with thepresent invention is used by being contained in a casing fitted with acylindrical member formed projectingly in the casing. This air filterelement is useful as a filter element for various air cleaner or airfilter for purifying contaminated air, and in particular, as an airfilter element for an internal combustion engine. Also, according to themethod of producing the air filter element in accordance with thepresent invention, the above-described air filter element can beproduced easily and reliably.

1. An air filter element used by closing both end surfaces of a hollowcylindrical filter portion by end plates, by forming an opening throughwhich a fluid passes in the center of at least one end plate, and byfitting said opening on a cylindrical member, wherein said one end platecomprises a soft inner peripheral seal portion capable of sticking tothe outer surface of said cylindrical member and a rigid closure portionwhich is disposed on the outer periphery side of said inner peripheralseal portion and in which the end surface of said filter portion isembedded, said end plate being of composite construction in which saidinner peripheral seal portion and said closure portion are integrallymolded, wherein on the outer periphery side of said inner peripheralseal portion, a groove axially extending from the end surface of saidend plate is formed along said opening, said groove being located on theinside in the radial direction of the inner peripheral surface of saidfilter portion, and on the outer periphery side of said groove, saidclosure portion is formed; and the inside wall portion of said groove isformed by said inner peripheral seal portion, and the outside wallportion of said groove is formed by said rigid closure portion.
 2. Theair filter element according to claim 1, wherein a plurality of ribswhich connect said inner peripheral seal portion and said closureportion to each other are provided in said groove.
 3. The air filterelement according to claim 1 or 2, wherein said inner peripheral sealportion is formed of soft expanded urethane resin, and said closureportion is formed of rigid urethane resin.
 4. A method of producing anair filter element used by closing both end surfaces of a hollowcylindrical filter portion by end plates, by forming an opening throughwhich a fluid passes in the center of at least one end plate, and byfitting said opening on a cylindrical member, wherein a mold is usedwhich is provided, with a ring-shaped inner peripheral, concave portionfor molding a soft inner peripheral seal portion, a ring-shaped convexportion for forming a groove in the end surface of the end plate, and aring-shaped outer peripheral concave portion for molding a rigid closureportion successively from the inside in the radial direction; asynthetic resin material, which is soft after curing, is poured intosaid ring-shaped inner peripheral concave portion; a synthetic resinmaterial, which is rigid after curing, is poured into said ring-shapedouter peripheral concave portion; and then the end surface of saidfilter portion is inserted into said ring-shaped outer peripheralconncave portion to integrally cure both of said synthetic resinmaterial, whereby an air filter element is produced in which said oneend plate comprises a soft inner peripheral seal portion capable ofsticking to the outer surface of said cylindrical member and a rigidclosure portion which is disposed on the outer periphery side of saidinner peripheral seal portion and in which the end surface of saidfilter portion is embedded, said end plate being of compositeconstruction in which said inner peripheral seal portion and saidclosure portion are integrally molded; on the outer periphery side ofsaid inner peripheral seal portion, a groove axially extending from theend surface of said end plate is formed along said opening; and on theouter periphery side of said groove, said closure portion is formed.